Numerous products available to consumers today are placed in packages that contain a quantity like items, such as hardware components (screws, washers, nuts, etc.) and office supplies (such as paper clips, etc.). These packages may be labelled according to the number of items contained therein or by the weight of the contents. However, in reality, the vast majority of these products are packaged by placing a predetermined volume of the product into the package and then weighing the filled package (or counting the items in the package) and then accordingly adjusting the volume placed in subsequent packages in order to obtain proper package weight. This method of dispensing products into packages is less than optimal as packages that are significantly under or over weight are either discarded or their contents recycled back into the filling system. It is also suboptimal as the contents of the package are not weighed prior to placement in the package and it is, thus, impossible to control particular package weights.
In addition, high speed systems have been developed to weigh particles. In systems of this type, the particles are dropped on to a platform from a fixed known height. The impact of the particles on the platform produces an electrical signal output in a load cell positioned beneath the platform. The load cell output is then used to calculate the particle weight. However, systems of this type are not without their inherent drawbacks and defects. For example, the accuracy of this type of weighing device is dependent on the characteristics of the material to be weighed. Thus, the scale must be adjusted for variations in particle density as well as variations in other surface characteristics. Another drawback of systems of this type is the fact that the measurement is based on the force exerted at the moment of impact and the entire measurement takes place in a "window" that is on the order of a few milliseconds (5-8 ms). Measurement signals thus obtained are subject to a high degree of resonant frequencies and noise which result in a degradation in overall measurement accuracy.
In view of the foregoing, it is accordingly an object of the present invention to provide a weighing system that is accurate.
Another object of the present invention is to provide a weighing system that is fast.
Still another object of the present invention is to provide a weighing system that may be incorporated into high speed packaging systems.
Yet another object of the present invention is to provide a weighing system wherein the weight calculation is based on a measurement signal of extended duration, thus, reducing undesired noise and resonance signals and yielding a more accurate weight measurement.
A still further object of the present invention is to provide a weighing system that is more efficient than systems of the prior art.
A still further object of the present invention is to provide a system that can also be employed as a continuous flow meter.